GreycapI strongly recommend Duck's settings, I based my own ones on them and they worked wonders even without tweaking.
Find them here.
identtiI use some of Fumes' settings from gtvault.com (not sure if I'm allowed to say that). They're excellent settings, and he's even produced a b-spec version!
Mr. QuackSpeaking of GTVault, there's 44 F1 set-ups there. You might want to try some of them out.
http://www.gtvault.com/gt4/setup-list/c_cid::747/
BMWteamPTGoohh, ducks work great for me. i have yet to beat Nurburgring but i beat Suzuka without a problem.
thanks by the way duck